1. Field of the Invention
The invention is a shaving preparation comprising 0.3 to 5% by weight of noncrystalline, amorphous silicon dioxide SiO2, which has not been produced pyrogenically, with a particle size of from 2 to 30 μm.
On account of a reduction in shaving force, the preparation leads to a more skin friendly, more thorough shave.
2. Discussion of Background Information
Shaving beard hair is part of a man's regular hygiene routine. For shaving, almost exclusively special razors were used in the past, the handling of which required some skill to avoid cut injuries and was therefore used predominantly by barbers, whereas nowadays blade razors with one or more blades are used, the handling of which is significantly safer, or electric razors are used.
To obtain a pleasant and thorough shave with the help of a blade razor, one requires, as assistants, water and a shaving product, a shaving preparation.
These shaving preparations are often in the form of foams or gels and are applied to the skin prior to shaving.
The preparations are supposed to prepare the hair for shaving, soften it and produce a gliding film which permits problem-free gliding of the blade over the skin.
A classic shaving product is shaving soap which is lathered using a brush and spread in the shaving zone. More recent products are shaving foams and self-foaming shaving gels.
The constructions of modern blade razors virtually exclude serious cut injuries. Nevertheless, irritations of the skin can arise if the blade does not glide in an optimal manner over the skin. Similarly, microcuts can occur on areas of uneven skin, particularly in the perifolicular region, aided by pulling or bending processes at the hair to be shaved. The desire for the most thorough shave possible, i.e. a cut as close to the skin as possible and an exclusion of irritations, i.e. a distance from blade to the skin, can only be combined with difficulty.
The key for the most optimum shave possible is the shaving product. Shaving products soften the hair, which makes the cutting operation easier and thus leads to less pressure on the hair and thus to fewer pulls. Known shaving products, foams and gels are based on basic preparations since, as is known, the soap-based and thus alkaline preparations lead to a swelling of the hair, and consequently a more thorough shave can take place.
At the same time, the shaving preparations form a lubricant film which reduces the friction and thus allows the blade to gently glide over the skin. Investigations show, however, also that hair that is too soft yields to the blade pressure and moves to one side as a result of bending, which shifts the cutting plane from horizontal into the vertical direction, and thus leads to frayed cutting edges, which is detrimental to the thoroughness. Something similar is observed if the gliding effect on the hair is also too great. The blade slips on the hair, does not find a holding point for a smooth cut, which often leads to a pulling out of the hair, and thus to an unpleasant sensation, and, as a result of these frayed ends, leads to an untidy, not very thorough shave.
Shaving auxiliaries are occasionally added to the known shaving preparations. These are particulate compounds or water-soluble polymers, such as PEG-14M, PEG-7M, PEG-90M (=PEG 90000), PEG 45M (polymers of ethylene oxide with average degrees of polymerization as numbered multiplied by factor 1000), acrylates, PTFE (polytetrafluoroethylene) or cellulose derivatives which are suitable for improving the glidability.
U.S. Pat. No. 6,342,211 B1 describes the process of the shaver slipping on the hair and the subsequent not very thorough shaving result. To solve this problem, 0.02-0.5% polyacrylamide suspended in water with a high molecular weight of MW=14 million is used in a shaving product which, according to the principle of a ball-bearing, brings about an optimum gliding effect of the shaver on the skin, but not on the hair.
U.S. Pat. No. 5,756,081 and U.S. Pat. No. 5,587,156 describe shaving preparations which comprise solid, insoluble, particulate additives (e.g. PTFE, PE, nylon, silica etc.), which offer the blade physical assistance, as a result of which cuts are prevented and the skin feel after shaving is improved.
EP 829 259 A1 describes shaving products which comprise microparticles (e.g. PA, kaolin, PTFE, PV, SiO2 etc.). These microparticles serve as exfoliating particles for removing dead skin cells. Silicon dioxide particles here can have a particle size of from 7 to 14 microns.
EP 1 439 816 B1 describes pyrogenically produced silicon dioxide in cosmetic preparations, where the SiO2 granules act as a carrier for cosmetic active ingredients and/or auxiliaries.
US 2007 0031366 A2 describes a process for achieving a more thorough shave. For this, the skin is treated inter alia with a pre-shave preparation which comprises skin-exfoliating particles such as silica, metal oxides, PE etc.
EP 1 704 897 B1 describes post-foaming shaving products consisting of water, C10-C24-alkanecarboxylic acid, neutralizing agent, nonionic surfactant, hydrophobic coemulsifier, C3-C9 polyol, thickening polymer, which is not PEG, PEG with an average molecular weight of at least 300 000 daltons and silica. By reducing the content of high molecular weight PEGs, as well as by adding silica together with a specific combination of soaps, nonionic surfactants, hydrophobic coemulsifiers, polyols and polymer thickeners, the aim is to improve the application properties, the skin feel, the foaming properties, and also the production and filling properties.
It is desirable to achieve a thorough shave with the lowest possible, or even better no, irritations of the skin.
In this connection, a cut of the hair as close to the skin as possible should be achieved, where the slipping of the razor blade on the hair is to be avoided and therefore fewer vertical cuts take place, meaning that the hair has fewer frayed ends.